x86, setup: Allow global variables and functions in the decompressor
In order for global variables and functions to work in the
decompressor, we need to fix up the GOT in assembly code.
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
LKML-Reference: <4C57382E.8050501@zytor.com>
diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S
index f543b70..67a655a 100644
--- a/arch/x86/boot/compressed/head_32.S
+++ b/arch/x86/boot/compressed/head_32.S
@@ -124,6 +124,19 @@
rep stosl
/*
+ * Adjust our own GOT
+ */
+ leal _got(%ebx), %edx
+ leal _egot(%ebx), %ecx
+1:
+ cmpl %ecx, %edx
+ jae 2f
+ addl %ebx, (%edx)
+ addl $4, %edx
+ jmp 1b
+2:
+
+/*
* Do the decompression, and jump to the new kernel..
*/
leal z_extract_offset_negative(%ebx), %ebp
diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S
index faff0dc..52f85a1 100644
--- a/arch/x86/boot/compressed/head_64.S
+++ b/arch/x86/boot/compressed/head_64.S
@@ -280,6 +280,19 @@
rep stosq
/*
+ * Adjust our own GOT
+ */
+ leaq _got(%rip), %rdx
+ leaq _egot(%rip), %rcx
+1:
+ cmpq %rcx, %rdx
+ jae 2f
+ addq %rbx, (%rdx)
+ addq $8, %rdx
+ jmp 1b
+2:
+
+/*
* Do the decompression, and jump to the new kernel..
*/
pushq %rsi /* Save the real mode argument */
diff --git a/arch/x86/boot/compressed/vmlinux.lds.S b/arch/x86/boot/compressed/vmlinux.lds.S
index 5ddabce..34d047c 100644
--- a/arch/x86/boot/compressed/vmlinux.lds.S
+++ b/arch/x86/boot/compressed/vmlinux.lds.S
@@ -41,6 +41,12 @@
*(.rodata.*)
_erodata = . ;
}
+ .got : {
+ _got = .;
+ KEEP(*(.got.plt))
+ KEEP(*(.got))
+ _egot = .;
+ }
.data : {
_data = . ;
*(.data)